I think this is attributed to not having his head in the game. At the typical interjunction when Foster fumbles, he should have realized that he should have both hands on the ball. But he doesn't.
That's why I'm so impressed with Chris Brown. Although he doesn't have the same amount of touches as Foster, he always seems like he protects the ball and is aware of getting out of bounds if the clock is winding down or keeping an eye on the first down marker. I think this is the mark of our coaching. Our coaching staff hasn't impressed upon enough of these young men how to think during the game.